The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies are committed to helping those interested in the sciences learn about the theory of evolution and how it is incorporated in all areas of scientific research.
This site provides teachers, students and general readers with a variety of learning resources about evolution. It contains key video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is an emblem of love and harmony in a variety of cultures. It also has many practical uses, like providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
Early approaches to depicting the world of biology focused on categorizing organisms into distinct categories which had been identified by their physical and metabolic characteristics1. These methods, which depend on the collection of various parts of organisms or short DNA fragments have significantly increased the diversity of a tree of Life2. The trees are mostly composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. We can construct trees by using molecular methods, such as the small-subunit ribosomal gene.
The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much biodiversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are often only represented in a single specimen5. Recent analysis of all genomes resulted in an initial draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that haven't yet been isolated or their diversity is not thoroughly understood6.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, assisting to determine if specific habitats require special protection. The information is useful in many ways, including identifying new drugs, combating diseases and improving crops. 에볼루션 카지노 사이트 is also extremely useful in conservation efforts. It can aid biologists in identifying the areas that are most likely to contain cryptic species with potentially important metabolic functions that may be at risk from anthropogenic change. While conservation funds are essential, the best way to conserve the biodiversity of the world is to equip the people of developing nations with the information they require to act locally and promote conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, shows the relationships between various groups of organisms. Utilizing molecular data similarities and differences in morphology, or ontogeny (the course of development of an organism), scientists can build an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic groups. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms with similar characteristics and have evolved from a common ancestor. These shared traits can be homologous, or analogous. Homologous traits are similar in terms of their evolutionary journey. Analogous traits may look similar however they do not have the same origins. Scientists combine similar traits into a grouping referred to as a the clade. All members of a clade have a common trait, such as amniotic egg production. They all evolved from an ancestor with these eggs. A phylogenetic tree is then constructed by connecting the clades to identify the organisms who are the closest to each other.
Scientists use DNA or RNA molecular information to create a phylogenetic chart that is more precise and precise. This information is more precise and provides evidence of the evolution of an organism. Molecular data allows researchers to identify the number of species that share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships between species can be influenced by several factors, including phenotypic plasticity a type of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more resembling to one species than another and obscure the phylogenetic signals. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous features in the tree.
Additionally, phylogenetics can help predict the length and speed of speciation. This information can assist conservation biologists in deciding which species to safeguard from disappearance. It is ultimately the preservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept in evolution is that organisms change over time as a result of their interactions with their environment. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could evolve according to its individual requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can cause changes that are passed on to the
In the 1930s and 1940s, concepts from various fields, including natural selection, genetics, and particulate inheritance--came together to form the current evolutionary theory, which defines how evolution occurs through the variation of genes within a population, and how those variations change over time as a result of natural selection. This model, which includes genetic drift, mutations, gene flow and sexual selection is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species by genetic drift, mutation, and reshuffling of genes in sexual reproduction, as well as by migration between populations. These processes, in conjunction with other ones like the directional selection process and the erosion of genes (changes in frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time as well as changes in the phenotype (the expression of genotypes in an individual).
Students can better understand phylogeny by incorporating evolutionary thinking in all aspects of biology. A recent study conducted by Grunspan and colleagues, for example revealed that teaching students about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. To find out more about how to teach about evolution, look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Scientists have looked at evolution through the past, analyzing fossils and comparing species. They also study living organisms. Evolution isn't a flims event, but an ongoing process. Bacteria transform and resist antibiotics, viruses evolve and are able to evade new medications, and animals adapt their behavior in response to the changing climate. The changes that result are often evident.
It wasn't until late-1980s that biologists realized that natural selection can be seen in action, as well. The key is that different traits have different rates of survival and reproduction (differential fitness) and can be passed down from one generation to the next.
In the past, if one particular allele, the genetic sequence that controls coloration - was present in a group of interbreeding species, it could quickly become more prevalent than the other alleles. As time passes, that could mean that the number of black moths within a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
The ability to observe evolutionary change is much easier when a species has a fast generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from one strain. Samples of each population have been taken regularly, and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's research has revealed that a mutation can profoundly alter the efficiency with which a population reproduces and, consequently, the rate at which it changes. It also proves that evolution takes time, a fact that some people find difficult to accept.
Another example of microevolution is the way mosquito genes that confer resistance to pesticides show up more often in populations in which insecticides are utilized. That's because the use of pesticides causes a selective pressure that favors those who have resistant genotypes.
The rapidity of evolution has led to a greater awareness of its significance especially in a planet shaped largely by human activity. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding the evolution process will help you make better decisions about the future of our planet and its inhabitants.